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e0c70b80 PT |
1 | /* |
2 | * ads7871 - driver for TI ADS7871 A/D converter | |
3 | * | |
4 | * Copyright (c) 2010 Paul Thomas <pthomas8589@gmail.com> | |
5 | * | |
6 | * This program is distributed in the hope that it will be useful, | |
7 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
8 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
9 | * GNU General Public License for more details. | |
10 | * | |
11 | * This program is free software; you can redistribute it and/or modify | |
12 | * it under the terms of the GNU General Public License version 2 or | |
13 | * later as publishhed by the Free Software Foundation. | |
14 | * | |
15 | * You need to have something like this in struct spi_board_info | |
16 | * { | |
17 | * .modalias = "ads7871", | |
18 | * .max_speed_hz = 2*1000*1000, | |
19 | * .chip_select = 0, | |
20 | * .bus_num = 1, | |
21 | * }, | |
22 | */ | |
23 | ||
24 | /*From figure 18 in the datasheet*/ | |
25 | /*Register addresses*/ | |
26 | #define REG_LS_BYTE 0 /*A/D Output Data, LS Byte*/ | |
27 | #define REG_MS_BYTE 1 /*A/D Output Data, MS Byte*/ | |
28 | #define REG_PGA_VALID 2 /*PGA Valid Register*/ | |
29 | #define REG_AD_CONTROL 3 /*A/D Control Register*/ | |
30 | #define REG_GAIN_MUX 4 /*Gain/Mux Register*/ | |
31 | #define REG_IO_STATE 5 /*Digital I/O State Register*/ | |
32 | #define REG_IO_CONTROL 6 /*Digital I/O Control Register*/ | |
33 | #define REG_OSC_CONTROL 7 /*Rev/Oscillator Control Register*/ | |
34 | #define REG_SER_CONTROL 24 /*Serial Interface Control Register*/ | |
35 | #define REG_ID 31 /*ID Register*/ | |
36 | ||
10775d18 GR |
37 | /* |
38 | * From figure 17 in the datasheet | |
39 | * These bits get ORed with the address to form | |
40 | * the instruction byte | |
41 | */ | |
e0c70b80 | 42 | /*Instruction Bit masks*/ |
088ce2ac GR |
43 | #define INST_MODE_BM (1 << 7) |
44 | #define INST_READ_BM (1 << 6) | |
45 | #define INST_16BIT_BM (1 << 5) | |
e0c70b80 PT |
46 | |
47 | /*From figure 18 in the datasheet*/ | |
48 | /*bit masks for Rev/Oscillator Control Register*/ | |
088ce2ac GR |
49 | #define MUX_CNV_BV 7 |
50 | #define MUX_CNV_BM (1 << MUX_CNV_BV) | |
51 | #define MUX_M3_BM (1 << 3) /*M3 selects single ended*/ | |
52 | #define MUX_G_BV 4 /*allows for reg = (gain << MUX_G_BV) | ...*/ | |
e0c70b80 PT |
53 | |
54 | /*From figure 18 in the datasheet*/ | |
55 | /*bit masks for Rev/Oscillator Control Register*/ | |
088ce2ac GR |
56 | #define OSC_OSCR_BM (1 << 5) |
57 | #define OSC_OSCE_BM (1 << 4) | |
58 | #define OSC_REFE_BM (1 << 3) | |
59 | #define OSC_BUFE_BM (1 << 2) | |
60 | #define OSC_R2V_BM (1 << 1) | |
61 | #define OSC_RBG_BM (1 << 0) | |
e0c70b80 PT |
62 | |
63 | #include <linux/module.h> | |
64 | #include <linux/init.h> | |
65 | #include <linux/spi/spi.h> | |
66 | #include <linux/hwmon.h> | |
67 | #include <linux/hwmon-sysfs.h> | |
68 | #include <linux/err.h> | |
e0c70b80 PT |
69 | #include <linux/delay.h> |
70 | ||
71 | #define DEVICE_NAME "ads7871" | |
72 | ||
73 | struct ads7871_data { | |
68f86c75 | 74 | struct spi_device *spi; |
e0c70b80 PT |
75 | }; |
76 | ||
77 | static int ads7871_read_reg8(struct spi_device *spi, int reg) | |
78 | { | |
79 | int ret; | |
088ce2ac | 80 | reg = reg | INST_READ_BM; |
e0c70b80 PT |
81 | ret = spi_w8r8(spi, reg); |
82 | return ret; | |
83 | } | |
84 | ||
85 | static int ads7871_read_reg16(struct spi_device *spi, int reg) | |
86 | { | |
87 | int ret; | |
088ce2ac | 88 | reg = reg | INST_READ_BM | INST_16BIT_BM; |
e0c70b80 PT |
89 | ret = spi_w8r16(spi, reg); |
90 | return ret; | |
91 | } | |
92 | ||
93 | static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val) | |
94 | { | |
95 | u8 tmp[2] = {reg, val}; | |
96 | return spi_write(spi, tmp, sizeof(tmp)); | |
97 | } | |
98 | ||
595a86af GR |
99 | static ssize_t voltage_show(struct device *dev, struct device_attribute *da, |
100 | char *buf) | |
e0c70b80 | 101 | { |
68f86c75 AL |
102 | struct ads7871_data *pdata = dev_get_drvdata(dev); |
103 | struct spi_device *spi = pdata->spi; | |
e0c70b80 PT |
104 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); |
105 | int ret, val, i = 0; | |
106 | uint8_t channel, mux_cnv; | |
107 | ||
108 | channel = attr->index; | |
10775d18 GR |
109 | /* |
110 | * TODO: add support for conversions | |
111 | * other than single ended with a gain of 1 | |
112 | */ | |
088ce2ac | 113 | /*MUX_M3_BM forces single ended*/ |
e0c70b80 PT |
114 | /*This is also where the gain of the PGA would be set*/ |
115 | ads7871_write_reg8(spi, REG_GAIN_MUX, | |
088ce2ac | 116 | (MUX_CNV_BM | MUX_M3_BM | channel)); |
e0c70b80 PT |
117 | |
118 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); | |
088ce2ac | 119 | mux_cnv = ((ret & MUX_CNV_BM) >> MUX_CNV_BV); |
10775d18 GR |
120 | /* |
121 | * on 400MHz arm9 platform the conversion | |
122 | * is already done when we do this test | |
123 | */ | |
e0c70b80 PT |
124 | while ((i < 2) && mux_cnv) { |
125 | i++; | |
126 | ret = ads7871_read_reg8(spi, REG_GAIN_MUX); | |
088ce2ac | 127 | mux_cnv = ((ret & MUX_CNV_BM) >> MUX_CNV_BV); |
e0c70b80 PT |
128 | msleep_interruptible(1); |
129 | } | |
130 | ||
131 | if (mux_cnv == 0) { | |
132 | val = ads7871_read_reg16(spi, REG_LS_BYTE); | |
133 | /*result in volts*10000 = (val/8192)*2.5*10000*/ | |
088ce2ac | 134 | val = ((val >> 2) * 25000) / 8192; |
e0c70b80 PT |
135 | return sprintf(buf, "%d\n", val); |
136 | } else { | |
137 | return -1; | |
138 | } | |
139 | } | |
140 | ||
595a86af GR |
141 | static SENSOR_DEVICE_ATTR_RO(in0_input, voltage, 0); |
142 | static SENSOR_DEVICE_ATTR_RO(in1_input, voltage, 1); | |
143 | static SENSOR_DEVICE_ATTR_RO(in2_input, voltage, 2); | |
144 | static SENSOR_DEVICE_ATTR_RO(in3_input, voltage, 3); | |
145 | static SENSOR_DEVICE_ATTR_RO(in4_input, voltage, 4); | |
146 | static SENSOR_DEVICE_ATTR_RO(in5_input, voltage, 5); | |
147 | static SENSOR_DEVICE_ATTR_RO(in6_input, voltage, 6); | |
148 | static SENSOR_DEVICE_ATTR_RO(in7_input, voltage, 7); | |
e0c70b80 | 149 | |
68f86c75 | 150 | static struct attribute *ads7871_attrs[] = { |
e0c70b80 PT |
151 | &sensor_dev_attr_in0_input.dev_attr.attr, |
152 | &sensor_dev_attr_in1_input.dev_attr.attr, | |
153 | &sensor_dev_attr_in2_input.dev_attr.attr, | |
154 | &sensor_dev_attr_in3_input.dev_attr.attr, | |
155 | &sensor_dev_attr_in4_input.dev_attr.attr, | |
156 | &sensor_dev_attr_in5_input.dev_attr.attr, | |
157 | &sensor_dev_attr_in6_input.dev_attr.attr, | |
158 | &sensor_dev_attr_in7_input.dev_attr.attr, | |
159 | NULL | |
160 | }; | |
161 | ||
68f86c75 | 162 | ATTRIBUTE_GROUPS(ads7871); |
e0c70b80 | 163 | |
6c931ae1 | 164 | static int ads7871_probe(struct spi_device *spi) |
e0c70b80 | 165 | { |
68f86c75 AL |
166 | struct device *dev = &spi->dev; |
167 | int ret; | |
e0c70b80 PT |
168 | uint8_t val; |
169 | struct ads7871_data *pdata; | |
68f86c75 | 170 | struct device *hwmon_dev; |
e0c70b80 | 171 | |
e0c70b80 PT |
172 | /* Configure the SPI bus */ |
173 | spi->mode = (SPI_MODE_0); | |
174 | spi->bits_per_word = 8; | |
175 | spi_setup(spi); | |
176 | ||
177 | ads7871_write_reg8(spi, REG_SER_CONTROL, 0); | |
178 | ads7871_write_reg8(spi, REG_AD_CONTROL, 0); | |
179 | ||
088ce2ac | 180 | val = (OSC_OSCR_BM | OSC_OSCE_BM | OSC_REFE_BM | OSC_BUFE_BM); |
e0c70b80 PT |
181 | ads7871_write_reg8(spi, REG_OSC_CONTROL, val); |
182 | ret = ads7871_read_reg8(spi, REG_OSC_CONTROL); | |
183 | ||
68f86c75 | 184 | dev_dbg(dev, "REG_OSC_CONTROL write:%x, read:%x\n", val, ret); |
10775d18 GR |
185 | /* |
186 | * because there is no other error checking on an SPI bus | |
187 | * we need to make sure we really have a chip | |
188 | */ | |
33fd2b84 GR |
189 | if (val != ret) |
190 | return -ENODEV; | |
c12c507d | 191 | |
68f86c75 | 192 | pdata = devm_kzalloc(dev, sizeof(struct ads7871_data), GFP_KERNEL); |
33fd2b84 GR |
193 | if (!pdata) |
194 | return -ENOMEM; | |
c12c507d | 195 | |
68f86c75 | 196 | pdata->spi = spi; |
c12c507d | 197 | |
68f86c75 AL |
198 | hwmon_dev = devm_hwmon_device_register_with_groups(dev, spi->modalias, |
199 | pdata, | |
200 | ads7871_groups); | |
201 | return PTR_ERR_OR_ZERO(hwmon_dev); | |
e0c70b80 PT |
202 | } |
203 | ||
204 | static struct spi_driver ads7871_driver = { | |
205 | .driver = { | |
206 | .name = DEVICE_NAME, | |
e0c70b80 | 207 | }, |
e0c70b80 | 208 | .probe = ads7871_probe, |
e0c70b80 PT |
209 | }; |
210 | ||
91efffe2 | 211 | module_spi_driver(ads7871_driver); |
e0c70b80 PT |
212 | |
213 | MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>"); | |
214 | MODULE_DESCRIPTION("TI ADS7871 A/D driver"); | |
215 | MODULE_LICENSE("GPL"); |